The move to "BBB-" with a stable outlook, coincided with Friday's decision by Fitch to affirm its rating for Russia at "BBB-" as well, although with a positive outlook, likewise due to Russia's improved fiscal policies.

S&P said Russia had kept its fiscal house in order while central bankers promoted financial stability and a recovery in private-sector lending.

The economy is expected to grow 1.8 percent this year before moderating to 1.7 percent over the following three years, S&P said in a statement.

"Economic recovery will likely be supported by the rebound in oil prices, a moderate expansion of domestic demand backed by gradual monetary easing, and the global economic upswing," the agency said.

"At the same time, adverse demographics and low productivity continue to weigh on Russia's long-term growth potential."

And with Washington poised to impose more sanctions on Moscow this year, geopolitical tensions could also be a drag on Russian growth, S&P said.

Fitch noted that Russia's budget deficit likely fell to 1.5 percent of GDP last year, dropping more than half from the year before, and was likely to fall again to 0.6 percent in 2018 on rising oil prices and higher non-oil revenues. — AFP